The present invention relates to the selective epoxidation of unsaturated (meth)acrylates allowing the production of new functional (meth)acrylates, and to the use of the latter for the synthesis of new polymers.
The epoxidation of unsaturated organic compounds by means of hydrogen peroxide and a heavy metal acid salt converted in situ into a corresponding peracid salt has been known for some time. Thus, U.S. Pat. Nos. 2,833,787 and 2,833,788 describe the epoxidation of non-conjugated ethylenic compounds, for example monoethylenic alcohols, by means of hydrogen peroxide and sodium pertungstate at a pH of between 3 and 7. Similarly, the article published in J. Org. Chem., Vol. 24, pages 54-55 (January 1959) describes the epoxidation of .alpha.,.beta.-unsaturated acids by means of hydrogen peroxide and sodium tungstate at a pH of between 4 and 5.5.
The epoxidation of olefins by means of hydrogen peroxide and molybdenum compounds is also disclosed in Angew. Chem. Int. Ed. Engl. 21 (1982) 734-750. Similarly, J. Org. Chem. (1983), Vol. 48, 3831-3833 describes the epoxidation of olefins at 70.degree. C. under phase transfer catalysis conditions by means of dilute hydrogen peroxide (at a concentration of less than 10%) and a water-soluble alkali metal tungstate, at pH 1.6 and in the presence of a phase transfer agent such as a quaternary ammonium or phosphonium halide, the molar ratio of hydrogen peroxide to the olefin being 0.6. The article published by J. Org. Chem. (1985) Vol. 50, 2688-2690 describes a similar reaction carried out at 50.degree. C. in the presence of complexes of molybdenum and monodentate ligands, the molar ratio of hydrogen peroxide to the olefin being 0.2.
Finally, it is known to epoxidize olefins at 60.degree. C. in chloroform, in the presence of a catalyst formed from molybdophosphoric or tungstophosphoric acid and cetylpyridinium chloride, by means of concentrated (35%) hydrogen peroxide and the molar ratio of hydrogen peroxide to the olefin being 1.5 or 1: on this subject reference may be made to J. Org. Chem. (1987), Vol. 52, 1868-1870 and J. Org. Chem. (1988), Vol. 53, 3587-3593.
Moreover, the U.S. Pat. No. 3,459,775 describes the epoxidation of vinylnorbornene (meth)acrylate at a temperature of 50.degree. C., for a period of 7 to 9 hours, by means of peracetic acid. 2-Epoxyethylbicyclo[2.2.1]hept-5(6)-yl (meth)acrylate is obtained under these conditions in a yield not exceeding 42%. Similarly, the patent application JP-A-62/81 378 describes the epoxidation of dicyclopentenyloxyethyl acrylate at a temperature of 60.degree. C., for 2 hours, by means of hydrogen, peroxide at a concentration of 35%. The epoxidized acrylate is obtained under these conditions in a yield not exceeding 48%.